兼容ipad的lazyload效果

function lazyload(option){
    alert("wwwwwwwwwwwwwwww");
    var settings={
        defObj:null,
        defHeight:0
    };
    settings=$.extend(settings,option||{});
    var defHeight=settings.defHeight,defObj=(typeof settings.defObj=="object")?settings.defObj.find("img"):$(settings.defObj).find("img");
    var pageTop=function(){

        var ua = navigator.userAgent.toLowerCase();
        if(ua.match(/iPad/i)=="ipad") {
            return document.documentElement.clientHeight+window.pageYOffset-settings.defHeight;
        } else {
            return document.documentElement.clientHeight + Math.max(document.documentElement.scrollTop, document.body.scrollTop) - settings.defHeight;
        }


        
    };
    var imgLoad=function(){
        defObj.each(function(){    
            if ($(this).offset().top<=pageTop()){
                var src2=$(this).attr("src2");
                if (src2){
                    $(this).attr("src",src2).removeAttr("src2");
                }
            }
        });
    };
    imgLoad();
    $(window).bind("scroll",function(){            
        imgLoad();
    });
}
lazyload({
    defObj:"#special1"
});
lazyload({
    defObj:"#special2"
});